Concomitant to a continuing trend towards miniaturization and increased functional density in electronic devices, considerable attention has been paid to so-called resonant-tunneling devices as characterized by operation involving carrier energy coinciding with a quantized energy level in a potential well. After early theoretical work, resonant-tunneling devices have been implemented at least experimentally, and an extensive literature has come into existence concerning theoretical and practical device aspects as surveyed, e.g., by
F. Capasso et al., "Resonant Tunneling Through Double Barriers, Perpendicular Quantum Transport Phenomena in Superlattices, and Their Device Applications", IEEE Journal of Quantum Electronics, Vol. QE-22 (1986), pp. 1853-1869.
Resonant-tunneling devices can be made as diodes and as transistors; see, e.g.,
E. R. Brown et al., "Millimeter-band Oscillations Based on Resonant Tunneling in a Double-barrier Diode at Room Temperature", Applied Physics Letters, Vol. 50 (1987), pp. 83-85;
H. Toyoshima et al., "New Resonant Tunneling Diode with a Deep Quantum Well", Japanese Journal of Applied Physics, Vol. 25 (1986), pp. L786-L788;
H. Morkoc et al., "Observation of a Negative Differential Resistance Due to Tunneling through a Single Barrier into a Quantum Well", Applied Physics Letters, Vol 49 (1986), pp. 70-72;
F. Capasso et al., "Resonant Tunneling Transistor with Quantum Well Base and High-energy Injection: A New Negative Differential Resistance Device", Journal of Applied Physics, Vol. 58 (1985), pp. 1366-1368;
N. Yokoyama et al., "A New Functional, Resonant-Tunneling Hot Electron Transistor (RHET)", Japanese Journal of Applied Physics, Vol. 24 (1985), pp. L853-L854;
F. Capasso et al., "Quantum-well Resonant Tunneling Bipolar Transistor Operating at Room Temperature", IEEE Electron Device Letters, Vol. EDL-7 (1986), pp. 573-575;
T. Futatsugi et al., "A Resonant-tunneling Bipolar Transistor (RBT): A Proposal and Demonstration for New Functional Devices with High Current Gains", Technical Digest of the 1986 International Electron Devices Meeting, pp. 286-289;
T. K. Woodward et al., "Experimental Realization of a Resonant Tunneling Transistor", Applied Physics Letters, Vol. 50 (1987), pp. 451-453;
B. Vinter et al., "Tunneling Transfer Field-effect Transistor: A Negative Transconductance Device", Applied Physics Letters, Vol. 50 (1987), pp. 410-412;
A. R. Bonnefoi et al., "Inverted Base-collector Tunnel Transistors", Applied Physics Letters, Vol. 47 (1985), pp. 888-890;
S. Luryi et al., "Resonant Tunneling of Two-dimensional Electrons through a Quantum Wire: A Negative Transconductance Device", Applied Physics Letters, Vol. 47 (1985), pp. 1347-1693; and
S. Luryi et al., "Charge Injection Transistor Based on Real-Space Hot-Electron Transfer", IEEE Transactions on Electron Devices, Vol. ED-31 (1984), pp. 832-839.
Considered as of particular interest are devices having currentvoltage characteristics including multiple negative resistance regions--this on account of potentially greatly reduced circuit complexity attendant to the use of such devices. However, while such multiple regions can be obtained from a plurality of resonances of a quantum well, resulting devices typically suffer from the drawback that current peaks corresponding to excited states carry significantly greater amounts of current as compared with the amount of current carried in the ground state.